Rotary cutting dies are used for producing a container or carton blank from corrugated board sheet material. These rotary cutting dies basically comprise a pair of cooperating cylinders. One of the cylinders, a cutting cylinder, includes a die board or base having cutting blades or rules while the other, the anvil cylinder, provides a backing surface against which the cut or score is made.
In the process of die cutting sheets of corrugated board, scrap is produced. The scrap may comprise outside trim cut from the sheet of corrugated board or it may comprise interior material cut from the final product, such as holes or slots. Because of the presence of cut pieces of scrap that occur during the process of performing work on a sheet of corrugated board, provisions for removing or stripping the scrap material from certain blades and the product board must be provided. If there is a failure of stripping or removing the cut scrap, the scrap material tends to collect around the cutting blade and can render the rotary cutting die inoperable. In addition, it is important to remove the cut scrap such that it does not become integrated with the produced corrugated board product.
It is known to use finger-type scrap strippers. See U.S. Pat. No. 7,111,534. These resilient and compressible fingers are attached to the die board of the rotary cutting die and project therefrom. They are, however, rearwardly angled, meaning that they are inclined or slanted in a direction opposite the direction of rotation of the rotary cutting die. That is, their orientation on the rotary cutting die is such that just before entering the nip between the rotary cutting die and the anvil, the fingers generally project rearwardly, again in a direction generally opposite to the direction of rotation of the rotary cutting die.
In recent years, it has become important for rotary cutting dies to operate more efficiently. That is, it has become important for rotary cutting dies to run at relatively high speeds and produce more product per hour than has been customary in the past. This is challenging for a number of reasons. One of the challenges is dealing with cut pieces of scrap at these high operating speeds. In some cases, the traditional rearwardly angled finger-type scrap strippers are not able to strip and move the cut pieces of scrap away from the rotary cutting die at these high speeds.
Therefore, there has been and continues to be a need for a rotary cutting die having a scrap stripping mechanism that is effective at high operating speeds.